Process for forming composite article

Abstract

A process for forming a hollow, cured composite article. The process includes steps of making a plug from a meltable material. The plug is covered with a polymerizable material and the covered plug is inserted into a cavity formed in a thermally-expansive and heat-resistant polymer held within a rigid container. The almost filled container is covered and the container and part are heated to cause curing of the polymerizable covering. The cured assembly is removed from the thermally-expansive and heat-resistant polymer and heated to an extent sufficient to melt the core.

What is claimed is: 
     
       1. A process for forming a hollow, cured composite article comprising the steps of: preparing a meltable plug having external dimensions equal to the internal shape of the cured composite article;   placing a polymerizable material about that portion of the plug which corresponds to the interior of the composite article to be formed;   inserting the polymerizable-material-covered plug into a cavity formed in a thermally-expansive and heat-resistant polymer and placing the polymer and plug assembly into a rigid container;   affixing the cover over the container and heating the contents of the container thereby causing the thermally-expansive polymer to expand and the polymerizable polymer to crosslink;   cooling the contents of the container;   removing the plug and its cross-linked covering from the container and from the cavity; and   heating the plug and its composite material part to a temperature sufficient to melt the plug thereby leaving a cured composite part.   
     
     
       2. The process of claim 1 further including, after said preparing step, the steps of: covering that portion of the plug which corresponds to the interior of the composite article to be formed with a removable substance about the thickness of the cured composite article thereby forming a covered plug;   placing the covered plug into a closeable, rigid container which does not significantly deform at an internal pressure of 700 psig;   filling the rigid container with a curable, thermally-expansive and heat-resistant polymer to an extent so that when the rigid container is closed, it will be filled between 90% and 100%;   curing the thermally-expansive polymer;   separating the cured polymer into sufficient parts so that the covered plug can be removed without tearing the cured polymer;   removing the covered plug from the polymer thereby leaving a cavity in the polymer; and   removing the removable substance from the covered plug.   
     
     
       3. The process of claim 1 wherein said rigid container has removable sides. 
     
     
       4. The process of claim 1 wherein said thermally-expansive polymer is a silicone polymer. 
     
     
       5. The process of claim 1 wherein said polymerizable matter is an epoxy resin. 
     
     
       6. The process of claim 5 wherein said polymerizable material further includes reinforcing fibers. 
     
     
       7. The process of claim 6 wherein said reinforcing fibers are graphite fibers. 
     
     
       8. The process of claim 1 wherein said meltable plug is fabricated from a metallic alloy. 
     
     
       9. A process for forming a mold form forming a cured composite article comprising the steps of: preparing a meltable plug having external dimensions equal to the internal shape of the cured composite article;   covering that portion of the plug which corresponds to the interior of the composite article to be formed with a removable substance about the thickness of the cured composite article thereby forming a covered plug;   placing the covered plug into a closeable, rigid container which does not significantly deform at an internal pressure of 700 psig;   filling the rigid container with a curable, thermally-expansive and heat-resistance polymer to an extent so that when the rigid container is closed, it will be filled between 90% and 100%;   curing the thermally-expansive polymer;   separating the cured polymer into sufficient parts so that the covered plug can be removed without tearing the cured polymer;   removing the covered plug from the polymer thereby leaving a cavity in the polymer; and   removing the removable substance from the covered plug.   
     
     
       10. The process of claim 9 wherein said removable substance is fabricated from a wax. 
     
     
       11. The process of claim 9 wherein said thermally-expansive polymer is a silicone polymer. 
     
     
       12. The process of claim 9 wherein said rigid container has removable sides.